In recent years, a phenomenon was discovered in which certain metal oxide materials have two states of a low resistance state and a high resistance state when a voltage is applied to the material due to the resistivity prior to the voltage application and the size of the applied voltage; and new nonvolatile memory devices utilizing such a phenomenon are drawing attention. Such a nonvolatile memory device is called ReRAM (Resistance Random Access Memory). When manufacturing ReRAM, it is necessary to form a current path called a filament inside a resistance change layer made of a metal oxide material by applying a high voltage to the resistance change layer. This is called the forming operation.
However, the manufacturing cost of conventional ReRAM undesirably increases because a considerable amount of time is necessary for the forming operation. As the memory cell becomes ultra-fine, it becomes difficult to control the forming operation to reliably form the filament; and the operational reliability of the ReRAM undesirably decreases.